Various methods and devices have been proposed for achieving positive airway pressure (PAP) for continuous positive airway pressure (CPAP), expiratory positive airway pressure (EPAP) and positive expiratory pressure (PEP) or positive end expiratory pressure (PEEP). Such techniques are used to enhance bronchial hygiene therapy by providing above atmospheric pressure at the airway during expiration (PEEP, PEP and EPAP) or continuously throughout the expiratory and inspiratory cycles (CPAP). Such techniques change the baseline pressure to aid in oxygenation by preventing collapse of unstable alveolar units due to lack of surfactant or disease, and maintain the alveoli open and restore functional residual capacity (FRC) of the patient.
A number of methods and apparatus for creating positive airway pressure have been used, including spring-loaded PEEP valves, magnetic valves, inflatable balloon threshold resistors and Venturi threshold resistors. An underwater or water seal PEEP valve uses fewer mechanical components, and is a practical, efficient and relatively inexpensive apparatus for adequately achieving the desired positive airway pressure. Such an apparatus is well known in the prior art, and described, for example, in U.S. Pat. No. 7,077,154, the description of which is incorporated herein by reference.
In the aforesaid patent, a drop tube is positionable at various discreet positions ensuring accurate depth and stability of the tube at the desired depth in the fluid. Although the design of the aforesaid disclosed apparatus is intended to ensure the secure positioning of the drop tube in the liquid at the desired depth, it does so at the expense of requiring various lengths of the elongated drop tube to extend upwardly out from the lid of the apparatus and is inconvenient to adjust.